INFO: task syz.6.1497:15168 blocked for more than 143 seconds.
      Not tainted syzkaller #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz.6.1497      state:D stack:25464 pid:15168 tgid:15165 ppid:14087  task_flags:0x400140 flags:0x00080002
Call Trace:
 <TASK>
 __schedule+0x17b4/0x5680
 schedule+0x164/0x360
 schedule_preempt_disabled+0x13/0x30
 rwsem_down_read_slowpath+0x6d9/0x940
 down_read+0x99/0x2e0
 super_lock+0x2d6/0x3d0
 __iterate_supers+0x126/0x250
 __ia32_sys_sync+0xa0/0x120
 do_syscall_64+0x15f/0xf80
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f81b299cdd9
RSP: 002b:00007f81b380a028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a2
RAX: ffffffffffffffda RBX: 00007f81b2c15fa0 RCX: 00007f81b299cdd9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 00007f81b2c15fa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f81b2c16038 R14: 00007f81b2c15fa0 R15: 00007ffe53e16288
 </TASK>

Showing all locks held in the system:
8 locks held by kworker/u8:1/13:
1 lock held by rcu_exp_gp_kthr/18:
1 lock held by khungtaskd/34:
 #0: ffffffff8e95cda0 (rcu_read_lock){....}-{1:3}, at: debug_show_all_locks+0x2e/0x180
3 locks held by kworker/0:3/5078:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc9000719fc40 (deferred_process_work){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
 #2: ffffffff8fdd0140 (rtnl_mutex){+.+.}-{4:4}, at: switchdev_deferred_process_work+0xe/0x20
2 locks held by getty/5438:
 #0: ffff8881135f30a0 (&tty->ldisc_sem){++++}-{0:0}, at: tty_ldisc_ref_wait+0x25/0x70
 #1: ffffc9000346b2e8 (&ldata->atomic_read_lock){+.+.}-{4:4}, at: n_tty_read+0x45c/0x13a0
3 locks held by kworker/1:6/7461:
 #0: ffff88810006b140 ((wq_completion)events){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc900048f7c40 (free_ipc_work){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
 #2: ffffffff8e9630a8 (rcu_state.exp_mutex){+.+.}-{4:4}, at: synchronize_rcu_expedited+0x2d0/0x770
2 locks held by syz-executor/12126:
1 lock held by syz.6.1497/15168:
 #0: ffff88816854c0d8 (&type->s_umount_key#63){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
3 locks held by kworker/u8:3/15683:
 #0: ffff88810fc3d940 ((wq_completion)ipv6_addrconf){+.+.}-{0:0}, at: process_scheduled_works+0xa35/0x1860
 #1: ffffc9000a7bfc40 ((work_completion)(&(&net->ipv6.addr_chk_work)->work)){+.+.}-{0:0}, at: process_scheduled_works+0xa70/0x1860
 #2: ffffffff8fdd0140 (rtnl_mutex){+.+.}-{4:4}, at: addrconf_verify_work+0x19/0x30
1 lock held by syz.7.1688/16687:
 #0: ffff88816854c0d8 (&type->s_umount_key#63){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
1 lock held by syz.7.1688/16688:
 #0: ffff88816854c0d8 (&type->s_umount_key#63){++++}-{4:4}, at: super_lock+0x2d6/0x3d0
1 lock held by syz.8.1908/18314:
 #0: ffffffff8fdd0140 (rtnl_mutex){+.+.}-{4:4}, at: tun_chr_close+0x3e/0x1c0
1 lock held by syz-executor/18372:
 #0: ffffffff8fdd0140 (rtnl_mutex){+.+.}-{4:4}, at: inet_rtm_newaddr+0x404/0x1ad0

=============================================

NMI backtrace for cpu 1
CPU: 1 UID: 0 PID: 34 Comm: khungtaskd Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 nmi_cpu_backtrace+0x274/0x2d0
 nmi_trigger_cpumask_backtrace+0x17a/0x300
 sys_info+0x135/0x170
 watchdog+0xfd3/0x1030
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
Sending NMI from CPU 1 to CPUs 0:
NMI backtrace for cpu 0
CPU: 0 UID: 0 PID: 3 Comm: pool_workqueue_ Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:zap_class+0xcf/0x340
Code: 49 81 fc 00 00 08 00 0f 84 a4 01 00 00 4e 8b 2c e5 e0 d3 fc 93 4d 85 ed 0f 94 c0 49 83 c5 f8 0f 94 c1 08 c1 75 d7 45 8b 75 00 <41> f6 c6 fc 0f 84 e1 00 00 00 41 c1 ee 08 4a 8d 1c 75 b0 d3 41 93
RSP: 0018:ffffc90000087c50 EFLAGS: 00000093
RAX: 00000000000b8033 RBX: ffffffff9358d416 RCX: 00000000000b8030
RDX: ffffffff93fcd3d8 RSI: 0000000000000005 RDI: 00000000000b4734
RBP: ffffffff9440d850 R08: ffffffff81af1998 R09: ffffffff8e95cda0
R10: dffffc0000000000 R11: fffffbfff206161f R12: 00000000000043f0
R13: ffffffff94672610 R14: 0000000005f89910 R15: 0000000000000d85
FS:  0000000000000000(0000) GS:ffff88818dc90000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fafc0ea1440 CR3: 000000016e466000 CR4: 00000000000006f0
Call Trace:
 <TASK>
 lockdep_unregister_key+0x1c3/0x350
 pwq_release_workfn+0x6d1/0x8c0
 kthread_worker_fn+0x4ee/0xb20
 kthread+0x388/0x470
 ret_from_fork+0x514/0xb70
 ret_from_fork_asm+0x1a/0x30
 </TASK>
